Damage vs Critical

[Miles Invictus]

Devastating Critical. Every time you critical with your chosen weapon, your opponent must make a Fortitude save or die (DC >= 34). Combine with an appropriate Vorpal weapon (you don't need keen, because Improved Critical is a prereq), and you've got a decent chance of instant-killing anything with a discernable anatomy.

Depending on your other equipment, you'd want to use a Kukri, Scimitar, or Falchion -- all three are martial weapons with good threat ranges.